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CROP WATCH

By Staff | Aug 3, 2012

This issue marks another week and another month off the calendar. Not much has changed except to say that last week’s run of 95 to 100-plus degree days sapped our energy as much as it sapped the corn and soybean plants as much as possible.

Many farmers still have mid-level hope for their corn and bean crops, but that is all dependent on getting measurable rains in the near future.

Most areas simply can’t catch a decent amount. The Gulf of Mexico moisture that has always been a dependable source of moisture over the last few decades just has not pushed much humidity up in our direction the past year.

Everyone is wondering how things look over a few counties, or how things are faring in other states, and what we think the national corn or bean yield will be. Those are all very good questions. To point out how tough any appraisal of the crop is going to be for any agronomist, grower, or government of private forecaster let me relate what I have seen so far.

I was out with a good grower over in eastern Iowa a week ago. We stood in his fields that look relatively good yet and showing few signs of stress. He has built the health of his soil, planted very healthy varieties, included AMS into his fertilizer program, used a root inoculant on both corn and beans, and his conventional herbicide program controlled his weeds quite well.

While out in his fields on the very hot day, we looked across a neighbor’s quarter section field that had a sand ridge running across it. The sandy area was gone and will yield zero. The lower ground looks better, but due to a compaction problem the leaves were rolling quite a bit. Thus that area will not yield very well, possibly 50 to 100 bushels per acre depending on if, when, and how much rain might fall before the full dent stage is reached.

Then his middle ground looks better, but is managed like so many others and is planted to a hybrid family that has shallow, scavenger-type roots. It was rolling on that day. So as to how well or poorly the field is going to yield, the only way to know is as it is being harvested and the yield monitor is churning out the factual yields for the combine operator to see.

Once yield checks and scale tickets are compared to the harvested acres, needed to verify or adjust the monitor, then we’ll have a better handle on how the yields will be.

My activities this past weekend consisted of loading up the F150 and trailer and driving to Ann Arbor, Mich., to attend the youngest daughter’s graduation ceremony, and then clear out her apartment to get ready for her to more to her place of employment. It was a 610-mile journey one way, but not a complicated one other than filling with fuel and negotiating the freeway traffic through the Gary, Ind., area.

It did give me a chance to see the eastern Iowa crops as well as those in Illinois, northern Indiana and southern Michigan. What we saw were crops that looked even worse than those of 2011. And I called last year’s Illinois crop a disaster.

There were fields that were still green and didn’t look too bad from the road, but they had very poor ear size and were on the serious downhill slide. In quite a few of the fields the plants were one to two feet short of being fence post high. That sounds a lot like the corn crops in South America last March, when they had their worst crop in 50 years.

Crop appearance

I still get to walk corn fields that appear to have 175-plus bpa potential. The ear fill is good and kernel depth is good. We just have to wonder where any moisture has come from the last few weeks and when more might fall. A review of the evapo-transpiration chart shows that corn at the milk stage, given this week’s weather parameters, will need to pull in about a quarter-inch per day.

There are apparently areas in central and northern Iowa that still have a scant moisture supply. Other places as in some of the counties in western Iowa appear to have depleted their supply during an August where less than a half-inch fell.

A meteorologist told me last week that his latest prediction was for the heat to break early in August and a hurricane would push moisture into the Midwest. We shall see.

I made a quick two-day trip up into western and northwest Iowa.

In areas, the corn still looks good. In other counties along the way the corn went downhill fast last week. Many spots in those fields are gone and the plants are completely brown now.

Rootworms

The reports continue to come in about fields that contain plants where all of the roots are found to have been chewed off by rootworm larvae, and the field had been planted to supposedly resistant hybrids. So what has been going on?

A few media sources have carried articles telling where a group of USDA entomologists are collaborating with Chinese entomologists and geneticists who are doing research to determine how resistance develops against such traits.

This international team is working with cotton to determine why and how the insects are able to change genetically to resist the action of the traits.

Such work is typically forbidden in this country, but the Chinese are worried about their food supply, so they proceeded with the work.

So much for intellectual freedom in certain countries. What they have been finding is that the old belief that resistant traits would always be recessive is not true anymore. They are finding several genes that provide tolerance to the Bt toxin that are dominant. This means that all the hype and ideas about refuge being a definite safeguard are not universally true.

This means that the development of resistant individual insects and the multiplication of their populations is not going to be restricted by having 5, 20 or 50 percent of the acreage planted to a susceptible plant genotype. That sounds just like the case for African bees where their genetics stay dominant and their ferocity can’t be crossbred down.

Soybean challenges

Many growers are recognizing that their soybean crop can produce decent yields if rain ever arrives. The crop is having challenges though. So far the podded node count is lower than normal, plus more flower and pod abortion than normal has taken place. Medium and fuller season varieties may show a yield advantage at harvest time if rains arrive by Aug. 9.

Producing high yielding varieties usually requires an aggressive management plan that consists of applying the newer, efficient inoculants to the seed and then using products that help to form more side branches on each plant.

Even with drought conditions, the application of hormone products and micronutrients has been producing the extra side branches that have formed podded nodes that add to the node count of the main stem.

With $16 per bushel soybeans, the reward will be there for the growers who took such an approach and will happen to catch the passing rains. Early beans that have been pushed ahead on maturity by the heat may not have the chance to capitalize on any late showers.

Tissue testing

More agronomists have been using tissue testing in recent seasons to help gauge how well applied fertilizer is getting into the plants and to see the status of their own plants.

The results from the plant samples we sent to the Netherlands for sap testing were phenomenal. I think there were about 20 minerals tested for, with a differentiation between old leaves and new leaves.

From this work we hope to learn how rapidly each mineral is absorbed into the plants and how much each moves systematically. Then their logic guidance helps to give information as to how each preceding mineral affects the uptake or availability of the following mineral.

It really becomes a four-dimensional system that requires a bit of abstract thinking to absorb and used to develop the treatment program for the crop.

What we do know from regular testing is that with such dry weather the flow of minerals into the plant can be slowed down measurably.

Their availability is reduced due to reduced microbial mineralization and reduced translocative flow.

Now that many growers will be wondering how the drought of 2011 and 2012 will affect nutrient uptake and plant availability to the 2013 crop, we should have more information on which to base our recommendations.

Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143.

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